Electrical distribution system



1940- w. H. FRANK EIAL 2,211,109

ELECTRICAL DISTRIBUTION SYSTEM Original Filed Dec. 4, 1936 INVENTORS MM J yM s nse Aug. 13, 1940 PATENT OFFICE ELECTRICAL DISTRIBUTION SYSTEM William H; Frank and Lawrence E. Fisher,

Detroit, Mich.

Original application December 4, 1936, Serial No.

114,261. Divided and this application February 14,1938, Serial No. 190,457

1 Claim.

This application relates to electrical distributlon systems of the bus duct type comprising duct or casing in which are disposed and suitably supported electrical conductors such as bus bars and is a division of our prior application Serial devices for engaging the bus bars and establishing connections between them and the termirials of the branch circuit take-ed devices. In that patent there is shown as an arrangement for supporting the bus bars within the duct in an insulated manner, transverse plates 28 of insulation which are so proportioned-as to divide the duct into cells, and. a substantially close fit was provided betweenthebus bars and the slots of the plates through which these passed, and a similar close fit was provided to insure the cells being sealed from one another to a substantial 2 degree.

' Now, it has been discovered that in the use of the duct illustrated in Patent bio-2,041,675 there occurred some few instances of burning of duct due to arcs formed incident to electrical surges,

3o leakage, loose connections, insulation breakdowns, and other causes and it was further discovered that this burning of duct was .due to the fact that the barriers 28 operated to prevent the free travel of arcs along th bus bars and that the thus confined arcs burned the duct or casing at points'near where the arcs were formed. Alter considerable study, it was discovered that burning of duct due to arcs could be eliminated and prevented by so designing the bus bar supports that they permitted the arcs formed to run the J full length of the duct freely and quickly and without interference to a point where they could be dissipated.safely, reliance being placed upon magnetic force created by the current in the bus bars to cause the arc to travel quickly along the duct to the dissipating center.

It was discovered that as'long as .the arc was permitted to travel freely and rapidly along the, bus bars, no damage to the duct would occur,

provided a suitable dissipating center was provided for the arcs which course the duct. However, as stated above; when anobstruction to the coursing oi the arc existed, suflllcient to stop the arc, the are burned the duct and in some instances the bus bars as well.

For example, the insulators shown at 28 01 Patent No. 2,041,675 provide such obstructions and consequently cause arcs to stop at the insulators, resulting in burning at such insulators, and in some cases causing arcs to beiormed in 5 neighboring cells due to the fact that gases arising on arcing in a cell would flow past the support into the'next cell and create new arcs in such other cell.

In this application there are disclosed bus supporting means designed to permit free coursing of arcs along the duct.

For an understanding of the supporting means here shown, reference should be had to the appended drawing. In the drawing,

Fig. 1 shows a duct in cross section provided with such arrangement for supporting bus bars:

Figs. 2 and 2a are sections on lines 2- 2 and Eli-2o, Figs. 1 and 2.

In the arrangement of Figs. l-2a, metal plates 2d are shown as welded to the duct 2i at longttudinally spaced intervals not too close to the openings, not shown, through which prongs may be inserted into the duct for engagement with the bus bars 22 which are apertured to permit 25 an insulation hollow pin or tube 23 to be passed therethrough ands have its ends received between the outwardly bent lugs 24 of the metal plates 20 whereby the tubes will be supported from the duct-and will be prevented from shifting up and down in the duct, it being observed that longitudinal shifting of the tubes and the bus bars, to compensate for misalignment, manuiacturing tolerance, and expansion due to temperature rises is permitted to some extent, with the parts restrained against excessive shifting by lugs 25 bent outwardly from the metal plates 20. The edges of the holes of the bus bars through which pass the tubes 23 are extruded or flanged as shown at 26 to provide the bus bars with their 40 original or full cross sections for current carrying purposes and to form suitable bearings for the bus bars and tubes, and between the bus bars and telescoped around the tubes 23 there are spacer tubes 21 arranged as shown.

The arrangement here shown has been found satisfactory for supporting bus bars in duct and has also been found to permit free coursing oi arcs in duct. 50

- We claim: I

-A bus duct comprising a long run of casing, elongated naked bus runs therein, these comprising long bus bars of ribbon iornnhaving opposed wide suriaces and opposed narrow edges, 55

2 2,211,109 and means for supporting the bus runs from the on opposite sides of the duct and passing through duct so constructed as not'to engage or cover holes of the bus runs opening to'the Wi 1 thenarrow edges of the bus runs and thus to faces of the bus runs, the pins being insulated avoid interfering with the free coursing of-arcs from the bus bars.

1 along such edges, the means comprising longi- WILLIAM H. FRANK.

tudinally spaced pins connecting and mounted LAWRENCE E. FISHER. 

